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What should I do if I put the wrong fuel in my car?

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Putting the wrong type of fuel in your car can be a costly mistake. As soon as you’ve put the wrong fuel in and turned the key, then caput! The engine is gone and you’re stuck at the garage.

Putting petrol in a diesel car, or diesel in a petrol vehicle, is a surprisingly easy mistake to make. From an over-tired parent simply reaching for the pump, to being distracted by another work email, or simply forgetting to check the pump, it’s no surprise to see so many drivers join this ever growing fuel mix-up statistic.

95% of mis-fueling happens when petrol is put into a diesel car, this is because diesel has a wider nozzle, which is harder to fit into a petrol car.


What to do when you put petrol in a diesel car?

Putting petrol in a diesel car can cause more damage than putting diesel in a petrol. If this does happen, don’t fret –  there is significant damage limitation if you realise you’ve put the wrong fuel in your car before you start the engine. All you have to do is call your breakdown provider or mobile mechanic and they’ll get it sorted – just make sure to go to your local garage that does wrong fuel repairs and get your car checked over!

Then it is just a case of draining your tank and refilling it with the correct fuel. If you spot your mistake quickly, you should be okay as it’s commonly agreed that you can mix up to 5% diesel in a petrol tank without breaking your car or the bank.

The real damage happens when you start the car and drive away. As soon as you turn the key in the ignition and the dashboard lights up, your fuel pump has come to life. The engine is supposed to be primed with diesel before it starts, but when you accidentally put petrol in it, it will be sucking the offending liquid into the fuel lines. So, not only will your tank then need to be drained, your fuel pipes will need to be flushed as well – which isn’t cheap!


What’s The Worst Case Scenario When You Put Petrol in a Diesel Car?

Knowing the worst case scenario has its positives – especially when it comes to putting the wrong fuel into your tank. After all, if you know the potential dangers of what could happen it might stop you from doing it. As we mentioned earlier, doing an R Kelly and sticking your key in the ignition is the worst thing you can do. If your engine does actually start, then you’re in for some real trouble.

This is because a modern diesel engine utilises a plethora of technology to save mpg figures and minimise emissions. The fuel pumps are greased with diesel as it passes through.

When petrol enters these diesel pipes, rather than lubricating the tubes, its solvent properties create internal friction. This is because the metal surfaces grind together, which causes them to disintegrate, and create a swarf. This means microscopic particles of metal could be created, causing further damage to your car’s engine.

After the petrol has gone through the pumps, the engine’s high-pressure injectors are the next thing to go. This is because they force fuel through the engine’s cylinders via incredibly fine holes with an engineered spray pattern. If this swarf gets into the injection system then it will block some or all of the holes. This really is the worst case scenario as a common rail injector system could cost thousands of pounds to replace.

If you think you’ve put the wrong fuel in your car then find and call a local garage or breakdown service to get it fixed as soon as possible!

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